1. Field of the Invention
The invention relates to a thermoelectric generator. More particularly, the invention relates to a thermoelectric generator with a heat source structure, a heat sink and thermoelectric module there between. The invention relates to a thermoelectric generator with a heat source having a fuel composition on a shaped support.
2. Discussion of the Related Art
Thermoelectric power (TE) generation is a solid-state process that converts heat to electricity. At the present stage of development of the process, the conversion of a heat producing fuel to electricity is relatively low. However, the process has desirable characteristics including the absence of moving parts or vibration, silence and ruggedness. For these reasons, the process has potential for replacing batteries in certain applications. These applications include military, space and civilian emergency applications where performance is of primary importance and cost is of lesser concern.
The electric power output of a thermoelectric generator is a function of the temperature difference across the thermoelectric device and the heat to power conversion efficiency of the thermoelectric device material. Thermoelectric efficiency of a material is measured by a figure of merit, Z. The figure of merit is specific to each material and can be calculated according to the formula:Z=S2ρ/K where:                S is the Seebeck coefficient,        ρ is the electrical conductivity, and        K is the thermal conductivity.Figure of merit has been found to vary with temperature. Therefore the term ZT is often used. ZT is the figure of merit Z at a specified temperature T.The Seebeck coefficient is defined as the ratio of the open-circuit voltage to the temperature difference between the hot and cold junctions of a circuit exhibiting the Seebeck effect. This is expressed as:S=V/(Th−Tc)where:        V is the open-circuit voltage,        Th is the hot junction temperature, and        Tc is the cold junction temperature.        
η is the efficiency of a device in converting heat to electricity. It is related to the figure of merit and the Seebeck coefficient by the equation:
  η  =                              T          h                -                  T          c                            T        h              ⁢                                        (                          1              +                              ZT                avg                                      )                    0.5                -        1                                          (                          1              +                              ZT                avg                                      )                    0.5                +                              T            c                    /                      T                          h              ⁢                                                                                      where:                ZTavg is the above described coefficient Z at a specific temperature Tavg,        Th is the hot junction temperature,        Tc is the cold junction temperature, and        Tavg is the average of Th and T.        
There is a need in the art for a thermoelectric generator that produces power at conventional battery voltages, is lighter than an power equivalent batteries, produces power longer than batteries and has an extended shelf life.